我們合成一系列的pyrimidine (py)化合物，這些化合物可以與三氯化銥以cyclometalation的方式配位，形成具有強磷光性質的銥金屬化合物。我們針對這些化合物進行光物理，電化學性質的探討，並選取部分銥金屬化合物製備成元件進行測試。 在光物理方面，配位基py的吸收光譜範圍從290~313 nm，發射光譜仍在紫外光範圍。當配位基與銥金屬形成錯化物後，其吸收光譜中360~500 nm的範圍歸屬為S0 →1MLCT、S0 →3MLCT和3π - π＊的躍遷；這幾種躍遷是因為銥金屬具有強的spin-orbit coupling的特性讓彼此能階相互混合，才可使得原本自旋禁制的三重態躍遷吸收較強。同時也因為銥金屬強spin-orbit coupling的特性使得這些錯化物於室溫時，在無氧溶液中多有不錯的量子產率；其放射出黃綠到橘紅色的磷光，波長範圍為522~558 nm。電化學方面，銥錯化物也可以測得銥(III)氧化成銥(IV)之氧化還原電位，並且可由此與吸收光譜得知化合物的HOMO與LUMO之能階。我們也發現到以上這些光物理和電化學性質都與配位基上之推拉電子基以及其所在位置有很大的關係。 We have synthesized a new series of pyrimidine compounds. These compounds undergo cyclometalation with iridium trichloride to form iridium (III) complexes which exhibit strong phosphorescence. The photophysical and electrochemical properties of these compounds were investigated. Electroluminescent devices were fabricated from selected iridium complexes. The absorption wavelengths of the py ligands range from 290 to 313 nm, and their emission wavelengths remain in the ultraviolet region. The 1MLCT, 3MLCT and 3π – π transition bands of these iridium complexes have been resolved in the range of 360~500 nm of the absorption spectrum. The 3MLCT and 3π – π transition gain intensity by mixing with higher lying 1MLCT state through the spin-orbit coupling of iridium(III). These iridium complexes emit yellow-green to orange-red phosphorescence with wavelengths ranging from 522 to 558 nm . Also the strong spin-orbit coupling leads to good quantum yields in air-free solution at room temperature. The iridium complexes exhibit a reversible oxidation due to Ir(III)→Ir(IV), and the HOMO and LUMO energy levels for each complex can be obtained from the cyclic voltammogram and the UV-vis absorption edge. We also found that the photophysical and electrochemical properties can be correlated with the electronic characters and the relative locations of the substituents on the ligands.
